This application claims the priority benefit of Taiwan application serial no. 89123792, filed Nov. 10, 2000.
1. Field of Invention
The present invention relates to the main board of a computer system. More particularly, the present invention relates to a computer main board structure for regulating constant power source.
2. Description of Related Art
Due to the rapid progress in semiconductor fabrication technologies, powerful central processing units (CPUs) capable of executing billions of instructions per second are constructed. Consequently, most recent personal computers operate at a bus speed related to the processor clock rate progressing in the gigahertz (GHz) frequency range. Even computer peripheral products can perform at a speed that parallels the CPU.
As the early computer system, the operating frequency is much lower than nowadays. Hence, signal reception for these types of computers are rarely affected by weak ground connections or an unstable voltage supply. However, the recent computer generally operates at a bus speed related to the processor clock rate progressing in the gigahertz frequency range. And the printed circuit board of the recent computer presents highly tight squeeze layout leg and outlet legs that requires a pierce-hole method to transmit signals from the top layer to the bottom layer. Consequently, producing an extensive ground layer or a power-source layer on a computer main board is almost impossible. Due to differences in power source and ground connection areas, signal received by the top signal layer and the bottom signal layer is bound to be unstable.
However, a printed circuit board with four layers is the most cost-effective means of production at present. Hence, a circuit board capable of regulating constant power source, strengthening ground connections, protecting signal integrity during transmission and shielding out external electromagnetic interference is in great demand.
Accordingly, one object of the present invention is to provide a circuit board and circuit sub-board capable of regulating constant power source and strengthening ground connections without increasing surface or volume of a main board so that the first and the fourth signaling layers on the main board are almost identical and that the cost of manufacture remains low.
To achieve these and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, the invention provides a circuit sub-board that can be applied to a computer system for regulating constant power sources and strengthening ground connections. The computer system includes a main board. The main board further includes a first power-source hole, a first ground-connection hole, a first power-source layer and a first ground-connection layer. The circuit sub-board includes a printed circuit board. The printed circuit board further includes a second power-source layer and a second ground-connection layer. The second power-source layer has second power-source holes and the second ground-connection layer has second ground-connection holes. The printed circuit board can be a double-layered circuit board, for example. The printed circuit board serves to stabilize voltage and strengthen ground connections. The second power layer is electrically connected to the first power-source hole via the second power-source hole. Hence, the first power-source layer is connected to the main board and the second ground-connection hole is above the printed circuit board. The second ground-connection layer is electrically connected to the first ground-connection hole via the second ground-connection hole so that the first ground layer of the main board is connected. The circuit sub-board is actually attached to the main board. In this invention, regions on the main board that corresponds to various components are excavated so that the circuit sub-board can attach to the main board. In addition, the second ground-connection layer is closer to the main board than the second power-source layer. Although power source stabilizing and ground-connection strengthening effects are weaker when the second power-source layer is closer to the main board, the effects are present nonetheless.
According to the embodiment of this invention, the structure formed by attaching the aforementioned circuit sub-board to the main board is achieved by piercing a plurality of guiding legs through the first power-source holes and the second power-source holes as well as piercing through the first ground-connection holes and the second ground-connection holes. The computer system further includes a chipset and a memory module slot. The circuit sub-board is in such a shape that most of the signaling lines between the chipset and the memory module slot are covered. Because the fourth signaling layer is electrically connected with and close to the circuit sub-board, this is equivalent to increasing the surface area of the ground connections and power source. Hence, the signaling lines are in a stable environment shielded from external electromagnetic interference.
This invention also provides a circuit board structure that can be applied to a computer system for regulating constant power sources and strengthening ground connections. The computer board structure includes a main board. The main board further includes a first printed circuit board, a first power-source layer, a first ground-connection layer, first power-source holes and first ground-connection holes. The first power-source holes are electrically connected to the first power-source layer. The first ground-connection holes are electrically connected to the first ground-connection layer and a circuit sub-board. The circuit sub-board serves to stabilize voltage. The printed circuit sub-board, for example, can be a double-layered circuit board such as a second printed circuit board having a second power-source layer and a second ground-connection layer. The second power-source layer has second power-source holes. The second ground-connection layer has second ground-connection holes and is above the second printed circuit board. The second power-source layer is electrically connected to the first power-source holes via the second power-source holes. The second ground-connection holes are above the second printed circuit board. The second ground-connection layer is electrically connected to the first ground-connection holes via the second ground-connection holes. The circuit sub-board is actually attached to the main board. Regions on the main board that corresponds to various components are excavated so that the circuit sub-board can attach to the main board. In addition, the second ground-connection layer is closer to the main board than the second power-source layer. Although power source stabilizing and ground-connection strengthening effects are weaker when the second power-source layer is closer to the main board, the effects are present nonetheless.
According to the embodiment of this invention, the structure formed by attaching the aforementioned circuit sub-board to the circuit board structure is achieved by piercing a plurality of guiding legs through the first power-source holes and the second power-source holes as well as the first ground-connection holes and the second ground-connection holes. The computer system further includes a chipset and a memory module slot. The circuit sub-board is in such a shape that most of the signaling lines between the chipset and the memory module slot are covered. Because the fourth signaling layer is electrically connected with and close to the circuit sub-board, this is equivalent to increasing the surface area of the ground connections and power source. Hence, the signaling lines are in a stable environment shielded from external electromagnetic interference.
It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the invention as claimed.